Typically, manufacturers in the area of wireless products wish to implement radio media interface circuits into radio terminals, such as PCMCIA cards or dongles, which typically must operate within the context of two or more radio standards but in accordance with one standard at any one time. These radio standards are for example collectively referred to as the IEEE 802 standard, which is well known to those of skill in the art. This standard is typically divisible into a number of individual radio standards including one standard at 5.8 GHz, known as 802.11a, and another two standards at 2.45 GHz, known as 802.11b and 802.11 g.
In terms of these radio standards, manufacturers are often interested in building radio terminals that will be able to operate at 802.11a, b, and g standards, with only one particular standard being active at any one time. As a result, the manufacturers are interested in acquiring a front-end module that incorporates receive and transmission elements such as the low noise amplifiers (LNA), power amplifiers (PA), impedance matching components, and RF switches for all the standards that the terminal or card must deal with. Thus providing them with flexibility in their radio terminal designs.
Unfortunately, PAs and other components such as the LNA, are highly specialized components that have specifications that generally do not overlap with other radio frequency bands. Thus, a 5.8 GHz PA is generally not suitable for use 2.4 GHz PA. As a result, distinct components such as the LNAs and PAs are incorporated into the module in order to accommodate different radio standards. Moreover, many of the high performance RF components such as PAs and LNAs have a relatively low level of ancillary circuit integration. For example, voltage regulation circuits, temperature regulation circuits, control circuits and other circuits that are used for control and optimization of the operation of the PA are often not integrated into a same die with the PA but rather disposed as discrete components, on separate semiconductor substrates, within the module surrounding the PA die. It is well understood by most module designers that adding more components to the module increases cost, reduces yield and durability while resulting in an increase in module size. This effect is compounded when additional circuitry is used for each active RF component such as an RF switch, LNA, and PA.
Recent advances in SiGe BiCMOS technology have allowed for progressively higher levels of integration of high-performance RF components. For example, a high-performance 2.45 GHz PA for the 802.11b/g standard implemented in SiGe BICMOS technology can incorporate voltage and temperature regulation circuitry along with various power optimization and control schemes manifested in control circuitry. The benefit of such high levels of integration are well understood by the IC design community and include reduced module sizes, reduced cost, reduced assembly time, and increased yield and module longevity. Moreover, for PAs in particular, the robustness of the PA in tolerating of mismatch conditions to the antenna can be improved with voltage standing wave ratio (VSWR) sensing circuitry and PA output power sensing circuitry integrated into the PA chip. In this particular example, a determination of high VSWR might lead to the generation of a control signal to reduce power output and thereby protect one or more PA gain stages from over voltage conditions. Clearly, integration of this type of ancillary circuitry into the PA has the potential to increase PA performance and robustness with a minimum increase in the module size. In respect of LNAs, the integration of bias point control circuitry is important.
However, the usage of SiGe BiCMOS technology in the industry is currently limited. For example, for 5.8 GHz PAs, only a small number of manufacturers are utilizing SiGe for whereas several end users are utilizing GaAs or group III-V based technologies. The GaAs based technologies however offer more gain per stage and lower losses in the RF signal path at 5.8 GHz. GaAs based technology, however, is often unsuitable for the integration of ancillary circuits for use with the GaAs based RF component. Voltage regulation, for example, may not be integrated into the GaAs based PA due to the lack of suitable elementary devices within the GaAs based technology. Therefore, in the context of a module, the module designer is compelled to add those additional circuits, or dies, for supporting of the GaAs based components. As mentioned previously, the addition of more components causes a detriment to the module size and cost.
A need therefore exists to for providing a compact RF module that supports a number of RF standards. It is therefore an object of the invention to provide a compact RF module that overcomes the limitations of the prior art by facilitating integration of multiple circuit components into a same module in order to support a number of RF standards.